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To Engrave on Wood

The block is commonly made of pear-tree or box, and differs in thickness according to its size. The surface for the engraving is on the transverse section of the wood; the subject is drawn upon it with a pen and Indian-ink, with all the finishing that is required to have in the impression. The spaces between the lines are cut away with knives, chisels, and gouges, leaving the lines that have been drawn with the ink.

The taking impressions from blocks of wood differs from that of copper-plate in this, that in the latter they are delivered from the incision, while drawing or chalking of the design to be engraved. by grinding; then spread it first thinly on the Now take white-lead and temper it with water, surface by a brush pencil, and afterwards rub it well with a fine linen rag, while yet wet, and when it is dry, brush off any loose or powdery part by a soft pencil.

If the design be sketched on the wood by drawing, it may be done by Indian or common ink (but the first is far preferable), either by a pen or pencil, or by a black-lead pencil, though that scarcely marks strongly enough for finer work.

Chiar Oscuro.

This method of engraving is performed with three blocks. The outline is cut in one, the deep shadows in a second, and the third gives a tint over the whole, except where the lights are cut away. These are substituted in their turn, each print receiving an impression from each block.

This mode of engraving was designed to represent the drawings of the old masters.

To Secure Copper-plates from Corrosion.

Take equal parts of wax and turpentine and double the quantity of olive oil, with the same quantity of hog's lard. Melt the whole over the fire in an earthen vessel, taking care to mix the ingredients well, and leave them to boil some time, till they are well incorporated.

The advantage of this mixture is, that it may at any time, being warmed, be put with the finger on the places desired to be covered; by which means the further operation of the aqua-fortis on such places may be instantly prevented without any other trouble or preparation, or without interrupting or delaying the principal operation. This mixture may be employed equally well with the hard as with the soft varnish. The intention of using such a composition is, if any scratches or false strokes happen in the etching they are to be stopped out with a hair-pencil dipped in this composition, mixed with lampblack, previously to laying on the aqua-fortis, or, as it is called, biting in.

To Choose Copper for Engraving.

Plates intended for engraving ought to be of the best copper, which should be very malleable, firm, and with some degree of hardness, free from veins or specks. The redness of copper is a presumptive mark of its being good, but not an infallible one; for though it is, in general, a proof of the purity of the copper, yet it does not evince that the qualities may not have been injured by too frequent fusion.

Copper-plates may be had ready prepared in most large towns, but, when these cannot be had, procure a pretty thick sheet of copper, rather larger than the drawing, and let the brazier planish it well; then take a piece of pumice-stone, and with water rub it all one way, till it becomes tolerably smooth and level. A piece of charcoal is next used with water for polishing it still farther, and removing the deep scratches made by the pumice-stone, and it is then finished with a piece of charcoal of a finer grain, with a little oil. To Etch upon Glass.

Procure several thick, clear pieces of crownglass, and immerse them in melted wax, so that each may receive a complete coating, or pour over them a solution of wax in benzine. When perfectly cold draw on them, with a fine steel point, | diamond dust, mixed up with oil of olives; and flowers, trees, houses, portraits, etc. Whatever parts of the drawing are intended to be corroded with the acid should be perfectly free from the least particle of wax. When all these drawings are finished the pieces of glass must be immersed one by one in a square leaden box or receiver, where they are to be submitted to the action of hydrofluoric acid gas, made by acting on powdered fluor-spar by concentrated sulphuric acid. When the glasses are sufficiently corroded they are to be taken out, and the wax is to be removed by first dipping them in warm and then in hot water, or by washing with turpentine or benzine .

Various colors may be applied to the corroded parts of the glass, whereby a very fine painting may be executed. In the same manner sentences and initials of names may be etched on wineglasses, tumblers, etc. Another Method.

Glass may also be etched by immersing it in liquid hydrofluoric acid, after having been coated with wax and drawn on, as in the last method .

There is this difference, however, in the use of the liquid and the gas, that the former renders the etching transparent, whilst that produced by the gas is quite opaque.

In this method the potassa of the glass is set free, whilst the silex or sand is acted on, consequently no vessel of glass can ever be employed with safety to contain this acid in a liquid state, as it would soon be corroded into holes. It is, therefore, generally preserved in leaden bottles, on which it has no power to act .

Glass in Imitation of Muslin.

This is a simple and ingenious means of giving to glass the appearance of delicately-wrought muslin. The process, which comes to us from Germany, consists in spreading very smoothly a piece of lace or tulle and covering it with some fatty substance by means of a printer's roller .

The glass being carefully cleaned, the cloth is laid upon it so as to leave in fat a print on the surface of all the threads of the fabric. The glass is then exposed about 5 minutes to the vapors of hydrofluoric acid, which roughens the spaces between the lines and leaves the polish on the surface under the fat.

A glass thus prepared becomes like a veil, protecting from exterior indiscretion persons who, from their apartment, desire to look commodiously outside.

To Transfer Engravings to Glass.

Fix the printed surface to the glass with ordinary paste. Etch with liquid hydrofluoric acid, s. g. 1.14. At the end of 3 or 4 minutes wash off the paper, and the design will be found reproduced upon the glass, the printers' ink having protected it. Mr. Napier, the patentee, prefers to have the glass ground enamelled or veneered beforehand, when the object stands out in relief. If the veneer or enamel is colored, of course the picture remains colored, while the body of the glass is white.

To Engrave on Precious Stones.

The first thing to be done in this branch of engraving is to cement two rough diamonds to the ends of two sticks large enough to hold them steady in the hand, and to rub or grind them against each other, till they be brought to the form desired. The dust or powder that is rubbed off serves afterwards to polish them, which is performed by a kind of mill that turns a wheel of soft iron. The diamond is fixed in a brass dish, and, thus applied to the wheel, is covered with when the diamond is to be cut facet-wise, first one face and then another is applied to the wheel.

Rubies, sapphires, and topazes are cut and formed the same way on a copper wheel, and polished with tripoli diluted in water. Agates, amethysts, emeralds, hyacinths, granites, rubies, and others of the softer stones, are cut on a leaden wheel moistened with emery and water, and polished with tripoli on a pewter wheel. Lapis-lazuli, opal , etc. are polished on a wooden wheel.

To fashion and engrave vases of agate, crystal, lapis-lazuli, or the like, a kind of lathe is made use of, similar to that used by pewterers, to hold the vessels, which are to be wrought with proper tools. The engraver's lathe generally holds the tools, which are turned by a wheel, and the vessel cut and engraved, either in relievo or otherwise, the tools being moistened from time to time with diamond dust and oil, or at least emery and water.

To engrave figures or devices on any of these stones, when polished, such as medals, seals, etc., a little iron wheel is used, the ends of whose axis are received within two pieces of iron, placed upright, as in the turner's lathe, and to be brought closer, or set further apart, at pleasure; at one end of the axis are fixed the proper tools, being kept tight by a screw. Lastly, the wheel is turned by the foot, and the stone applied by the hand to the tool, then shifted and conducted as occasion re-- quires.

The tools are generally of iron, and sometimes of brass. Their form is various some have small round heads, like buttons; others like ferrels, to take the pieces out, and others flat, etc. When the stone has been engraved it is polished on wheels of hair-brushes and tripoli.